JPH05164194A - Toothed belt and its manufacture - Google Patents

Abstract

PURPOSE:To provide a toothed belt superior in a tooth breakage resistant perfor mance at high temperature by using jointly two kinds of specific organic chemi cal compounds as the common cross-lining agent for a hydrogenated organic peroxide nitrile rubber composition that constitutes tooth rubber and back rubber. CONSTITUTION:In a toothed belt consisting of tooth rubber 2, back rubber 4, a tension member 5 and tooth cloth 3, tooth rubber 2 and back rubber 4 are made up of a hydrogenated organic peroxide nitrile rubber composition that uses jointly one kind or more than two kinds chosen from a group consisting of organic acid high class ester and the metal salt of acrylic acid or methacrylic acid, and N,N'-m-phenylenedimaleimide, as a common cross- linking agent. As this toothed belt is superior ion heat resistant and tooth breakage resistant performance at the times of high temperature and high load, it is especially useful as a toothed belt for automobile engine cam shaft drive that demands high performance and high load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved toothed belt for power transmission, and more particularly to an improved toothed belt for driving a camshaft of an automobile engine.

[0002]

2. Description of the Related Art A conventional camshaft driving toothed belt (hereinafter abbreviated as a belt) of an automobile engine mainly uses chloroprene as a main raw material rubber. These days
As the performance and sophistication of automobiles have increased, so has the demand for higher performance of automobile engines, which raises the environmental temperature where belts are used and increases the load on camshaft drives. Conventional chloroprene is used as the main raw material. A belt that uses rubber as the main rubber has insufficient heat resistance, and it has become insufficient to cope with high loads. On the other hand, belts whose main body is rubber made from chlorosulphonated polyethylene as the main material and belts whose main body is rubber made from sulfur-crosslinked hydrogenated nitrile have been developed. With the further advancement of high performance, the heat resistance and high load required for them are still insufficient.

Further, recently, in order to improve heat resistance,
It has been proposed to use a peroxide-crosslinked hydrogenated nitrile rubber composition containing a terminal-carboxylated polybutadiene as a co-crosslinking agent for the main rubber of a toothed belt. (JP-A-1-269743)

[0004]

However, although the toothed belt described in JP-A-1-269743 is very excellent in heat resistance, it is resistant to tooth loss, especially at high temperature and high load. It was clarified that the tooth-breaking performance in the above was not yet sufficient.

[0005]

SUMMARY OF THE INVENTION The present invention provides a toothed belt for power transmission which has excellent heat resistance and high elasticity, and also has excellent heat resistance life and tooth loss life even at high temperature and high load. It is intended to be provided. The present inventors have conducted extensive studies to achieve the above object, and as a result, when using two kinds of co-crosslinking agents in combination in a peroxide-crosslinking system hydrogenated nitrile rubber, heat resistance and tooth dent resistance The present invention has been completed by finding that the number is dramatically increased. That is, the toothed belt of the present invention is the first
As shown in the figure, the tooth rubber 2 is projected on the back rubber 4 in which the tensile body (core wire) 5 is embedded to form the tooth 1. A tooth cloth 3 is adhered to the exposed surfaces of the tooth rubber 2, the back rubber 4 and the tension antibody 5. In order to manufacture this toothed belt, a tooth cloth impregnated with a rubber paste is wound around a mold having a groove in the shape of a belt tooth, and a tensile member subjected to an adhesive treatment is wound around the tooth cloth, and further on that. An unvulcanized rubber compounding sheet that serves as a tooth rubber and a back rubber is wrapped around, molded and vulcanized in a pressure can, taken out, and cut into a certain width to obtain an annular belt.

The main rubber constituting the tooth rubber and back rubber, which is one of the features of the present invention, is selected from the group consisting of higher organic acid esters and metal salts of acrylic acid or methacrylic acid as co-crosslinking agents. One or more,
Containing N, N'-m-phenylenedimaleimide,
An organic peroxide-crosslinked hydrogenated nitrile rubber composition is used. As the tooth cloth, a cloth formed by weaving polyamide fiber, polyaramid fiber, polyester fiber or the like is used. Then, prior to adhering this tooth cloth to the surfaces of tooth rubber and back rubber, a rubber paste prepared by adding an organic compound having an isocyanate group to a rubber liquid obtained by dissolving a hydrogenated nitrile rubber composition similar to the main rubber in an organic solvent. Impregnate. For the tensile body, a core wire formed by twisting glass fiber, aramid fiber, metal fiber, etc. is usually used. This tensile body is also impregnated with the adhesive solution prior to use. As this adhesive, a solution (RFL) obtained by mixing latex with an aqueous solution of RF resin obtained by reacting resorcinol and formalin is generally used. Further, a tension antibody in which rubber paste or the like is overcoated on the surface of the core wire impregnated with the RFL may be used.

The hydrogenation rate of the hydrogenated nitrile rubber used for the main rubber is preferably 80% to 95%,
About 90% is particularly preferable. The hydrogenation rate is 98%
When it is more, the modulus value at high temperature is lowered, so-called softening is caused, and the tooth chipping resistance at high temperature is lowered, which is not preferable. If the hydrogenation rate is less than 80%, the heat resistance will be poor, and this is also not preferable. As the organic peroxide used as a cross-linking agent, any of diacyl peroxide type, peroxy ester type, dialkyl peroxide type, and perketal type may be used, but processability, safety, storability, reactivity, etc. are taken into consideration. , For example, di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide,
1.1-Di-t-butylperoxy-3.3.5-trimethylcyclohexane, 2.5-di-methyl-2.5-di (t-butylperoxy) hexane, 2.5-di-methyl-2.5 -Di (t-butylperoxy) hexane-3, bis (t-butylperoxydi-isopropyl) benzene,
2.5-di-methyl-2.5-di (benzoylperoxy) hexane, t-butylperoxybenzoate, t-
Butyl peroxy 2-ethyl-hexyl carbonate and the like can be mentioned as practically preferable. Of these, 4 types of dicumyl peroxide, t-butyl cumyl peroxide, 2.5-di-methyl-2.5-di (t-butylperoxy) hexane and bis (t-butylperoxydi-isopropyl) benzene are preferable, Further, taking into consideration mass productivity, dicumyl peroxide and bis (t-butylperoxydi-isopropyl) benzene are particularly preferable. Further, since dicumyl peroxide gives off-flavor to the product, the most practically suitable one is bis (t-butylperoxydi-isopropyl) benzene. In addition, bis (t-butylperoxydi-isopropyl) benzene includes 1,3 bis (t-butylperoxydi-isopropyl) benzene and 1,4 bis (t-butylperoxydi-isopropyl) benzene as isomers, and any of them is used. it can. Generally, commercially available organic peroxide preparations are prepared by powdering 1,3 or 1,4 bis (t-butylperoxydi-isopropyl) benzene alone or a mixture of both on a carrier such as calcium carbonate or silica. It is provided as it is or in the form of pellets. In any case, it can be said that there is almost no difference between 1, 3 and 1, 4 for the purpose of use of the present invention.

The amount of the organic peroxide crosslinking agent used is --O-- based on 100 g of the hydrogenated nitrile rubber polymer.
The amount of O-group is 0.30 to 1.51 g. If the amount of the organic peroxide cross-linking agent used is less than 0.30 g, the tooth dent resistance will be poor. On the other hand, if the amount used is more than 1.51 g, the heat resistance will be poor, the moldability of the belt will be poor, and the incidence of defective products will be high, making mass production difficult. As the co-crosslinking agent, one or more selected from the group consisting of organic acid higher esters and metal salts of acrylic acid or methacrylic acid and N, N'-m-
Used in combination with phenylene dimaleimide. As described above, the combined use of two specific types of co-crosslinking agents is the most important point of the present invention, and the use of only one of them cannot provide sufficient effects.

Examples of higher organic acid esters as co-crosslinking agents include ethylene dimethacrylate, 1,3 butylene dimethacrylate, 1,4 butylene dimethacrylate, 1,6 hexanediol dimethacrylate, polyethylene glycol dimethacrylate, 1,3. 4 butanediol diacrylate, 1,6 hexanediol diacrylate, 2,2'bis (4-methacryloxydiethoxyphenyl) propane, 2,2'bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane tri Acrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, 3-chloro-2-hydroxypropyl methacrylate, oligoester acrylate, triallyl isocyanurate, triallyl Cyanurate, triallyl trimellitate, diallyl phthalate, diallyl chlorendate can be mentioned. Examples of the metal salt of acrylic acid or methacrylic acid as the co-crosslinking agent include aluminum methacrylate, aluminum acrylate, zinc methacrylate, zinc dimethacrylate, zinc acrylate, magnesium dimethacrylate, magnesium acrylate, calcium dimethacrylate, and calcium acrylate. .. Of these, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl cyanurate, zinc methacrylate, zinc dimethacrylate and zinc acrylate are particularly preferable.

The amount of the higher organic acid ester or the metal salt of acrylic acid or methacrylic acid used in combination with N, N'-m-phenylenedimaleimide as a co-crosslinking agent is 0 based on 100 g of the hydrogenated nitrile rubber polymer. .5
~ 2.0 g. If the amount used is less than 0.5 g, the tooth-breaking performance becomes poor. On the other hand, if the amount used is more than 2.0 g, the heat resistance will be poor, the moldability of the belt will be poor, and the incidence of defective products will be high, making mass production difficult. Similarly, the amount of N, N'-m-phenylene dimaleimide used as a co-crosslinking agent which is used in combination with a higher organic acid ester or a metal salt of acrylic acid or methacrylic acid is also based on 100 g of the hydrogenated nitrile rubber polymer. It is 0.5 to 2.0 g. This usage is 0.5g
If it is less, the tooth-breaking performance becomes poor. On the contrary, if the amount used is more than 2.0 g, the heat resistance will be poor,
The moldability of the belt deteriorates and the incidence of defective products increases, which makes mass production difficult. In addition, when only one of the organic acid higher ester, the metal salt of acrylic acid or methacrylic acid, or N, N'-m-phenylene dimaleimide is used alone as the co-crosslinking agent, the tooth-breaking performance is particularly poor. The result is obtained.

As described above, the tooth cloth is impregnated with a rubber paste prepared by previously dissolving a hydrogenated nitrile rubber composition similar to the main rubber in an organic solvent and adding an organic compound having an isocyanate group to the rubber liquid. As the organic compound having an isocyanate group, for example, polymethylene polyphenyl isocyanate, triphenyl methane triisocyanate,
Tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate, metaxylene diisocyanate, hexamethylene diisocyanate, lysine isocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane 2,4 (2,6) diisocyanate, 1, Examples thereof include 3- (isocyanatomethyl) cyclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, and dimer acid isocyanate.

[0012]

EXAMPLES Examples of the present invention will be described in detail below.
Table 1 shows a compounding example of the organic peroxide-crosslinked hydrogenated nitrile rubber composition used in this example.
That is, a bis (t-butylperoxydi-isopropyl) benzene preparation as an organic peroxide in nitrile rubber having a hydrogenation rate of 90% (Zetpol 2020 manufactured by Nippon Zeon Co., Ltd., Peroximon F-40 manufactured by NOF CORPORATION). Or Kadaku Akzo Co., Ltd., PARKADOX 14/40) and N, N'-m-phenylenedimaleimide as a co-crosslinking agent added with a higher organic acid ester or a metal salt of methacrylic acid in various compounding ratios. Example 1
~ 9. In addition, since the bis (t-butylperoxydi-isopropyl) benzene preparation in Tables 1 to 3 contains 60% of an additive consisting of calcium carbonate, silica or a mixture of both, 5 g of the bis (t-butylperoxydi-isopropyl) benzene preparation was prepared. If this is the case, the net weight of this compound will be 2 g. Furthermore, in terms of —O—O— group, this compound contains two —O—O— groups, so 2 g × 16 × 2 × 2 (2 —O—O— group molecular weight)
÷ 338 (molecular weight of this compound) = 0.38 g.
Similarly, when the amount of the formulation added is 3 g, the net amount is 0.23 g, and when the formulation amount is 21 g, the net amount is 1.59 g.

[0013]

[Table 1]

In Table 2, as Comparative Example (I), the polymer of the present invention and the crosslinking agent are the same, and the co-crosslinking agent used in the present invention is used alone. Comparative examples 6 to 11 show the mixed examples.

[0015]

[Table 2]

Further, in Table 3, as Comparative Example (II), various compounding examples using chloroprene rubber or chlorosulfonated polyethylene as a polymer are Comparative Examples 12 to 16.
It shows with.

[0017]

[Table 3]

Table 4 shows the performance of the rubber alone and the performance of the belt for the rubber compositions shown in Table 1 of the present invention.

[0019]

[Table 4]

The rubber performance and the belt performance corresponding to Comparative Example (I) are shown in Table 5, respectively.

[0021]

[Table 5]

Further, the performance of the rubber alone and the performance of the belt corresponding to Comparative Example (II) are shown in Table 6, respectively.

[0023]

[Table 6]

The belt performance was measured with respect to heat resistance performance and tooth loss resistance performance, and the measurement method was as follows. First, the heat resistance is as follows: a drive pulley with 19 teeth (pitch 8 mm), a driven pulley with 19 teeth and a diameter of 45 m.
Using a tester composed of m idlers, the tension of the belt under test is always maintained at 15 kgf and the rotation speed is 4000 r.
/ Min, no load, the time during which the belt under test is run while the belt running atmosphere is kept at 140 ° C by continuously supplying fresh hot air, and the back surface of the belt under test or the root of the tooth is cracked Was evaluated by a heat resistant running test (hereinafter, abbreviated as A test, if necessary). Tooth resistance of the belt is measured by applying a shearing force of 25 kgf to the teeth of the belt under test with a width of 19.05 mm at a temperature of 100 ° C. repeatedly at a rate of 500 times per minute perpendicular to the width direction of the belt at room temperature or 100 ° C. It was evaluated by a tooth-breakage resistance test (abbreviated to B test as necessary) in which the time until chipping was measured.

In Table 1 showing formulation examples of the present invention, N, N'-m-phenylene dimaleimide is used as a co-crosslinking agent for a nitrile rubber polymer having a hydrogenation rate of 90%, and a higher organic acid ester or methacrylic acid is used. As shown in Table 4, the results show that the heat resistance performance is extremely high at a minimum of 808 hours and a maximum of 912 hours, as shown in Table 4. Also, in terms of tooth dent resistance, the belt life at room temperature is at least 290 hours, and the belt life at 100 ° C. is at least 199 hours, which are both extremely high values.

On the other hand, Comparative Examples 1 to 4 are those in which the co-crosslinking agent used in the present invention is used alone.
Although the test (heat resistance performance) shows excellent performance, the B test (dentless resistance performance) cannot give sufficient performance. Further, in Comparative Example 5, the terminal carboxylated polybutadiene used in the invention of JP-A-1-269743 cited as a prior art is used alone. It can be seen that it is considerably inferior to that of the present invention. Particularly, the belt life at a high temperature of 100 ° C. is 140 hours, which is considerably lower than that of the present invention. Furthermore, in Comparative Example 6, trimethylolpropane methacrylate (TMP), which is the co-crosslinking agent used in the present invention, and N, N'- were used for a nitrile rubber polymer having a hydrogenation rate of 90%. This is an example in which m-phenylene dimaleimide is used in combination, but the mixing ratio is such that 1 g of TMP is used for 100 g of polymer, N,
This is an example in which 2.5 g of N'-m-phenylenedimaleimide was used, that is, more than 2.0 g which is the upper limit of the limited range. In this case, although the A test (heat resistance performance) and the B test (dentation resistance performance) both show excellent performance, the scorch time is remarkably short and stable production is difficult, so this formulation example Not preferable.

In Comparative Example 7, a nitrile rubber polymer having a hydrogenation rate of 90% was used, and the co-crosslinking agent used in the present invention was trimethylolpropane methacrylate (T).
MP) and N, N'-m-phenylene dimaleimide are used in combination. The compounding ratio of TMP is 0.4 g and N, N'-m-phenylene dimaleimide is 0 g based on 100 g of the polymer. This is an example in which the amount used is less than 0.5 g, which is the lower limit of the limiting range. In this case, the A test (heat resistance performance) shows a slightly satisfactory value, but the B test (dentation resistance performance) shows only a very low value. In Comparative Examples 8 and 9, the blending ratio of bis (t-butylperoxydi-isopropyl) benzene of organic peroxide was changed. That is, 3 g in Comparative Example 8
This corresponds to 0.23 g in terms of the amount of —O—O— group, which is below the lower limit of 0.30 g of the limited range. In this case, the A test (heat resistance performance) shows a slightly satisfactory value, but the B test (dentless resistance performance) shows only a low value. In Comparative Example 9, 21 g of the same organic peroxide as described above is used. This corresponds to 1.59 g in terms of the amount of —O—O— group, which is the upper limit of the limited range of 1.
It exceeds 51 g. In this case, the A test (heat resistance performance) shows a very bad result, but the B test (tooth loss resistance performance) shows almost satisfactory values.

Comparative Example 10 is an example in which the same polybutadiene as in Comparative Example 5 was used in combination with N, N'-m-phenylene dimaleimide, but the results are the same as in Comparative Example 5 and hardly improved. Comparative Example 11 is an example in which trimethylolpropane methacrylate (TMP) and N, N'-m-phenylene dimaleimide are used in combination, but the compounding ratio thereof is 100 g of polymer and 2.MP of TMP. 5g,
In this example, 2.5 g of N, N'-m-phenylenedimaleimide was used, which was more than the upper limit of 2.0 g of the limited range. In this case, the A test (heat resistance performance) is extremely poor, and the B test (dentation resistance performance) shows a little inferior result. Comparative Examples 12 to 14 of the group of Comparative Example (II) are belts made of a rubber containing hydrogenated nitrile rubber in which sulfur is cross-linked, Comparative Example 15 is a belt made of chloroprene rubber, and Comparative Example 16 is chlorosulfone. The respective performances of the belts made of the modified polyethylene rubber are shown, but it is clear that the performances in both the A test and the B test are inferior.

[0029]

In the toothed belt according to the present invention, the tooth rubber and the back rubber are used as the co-crosslinking agent and one or more kinds selected from the organic acid higher ester and the metal salt of acrylic acid or methacrylic acid and N. , N'-m-phenylene dimaleimide and a cured polymer of a hydrogenated nitrile rubber composition of an organic peroxide cross-linking system, and a tooth cloth having the same rubber composition as a tooth rubber and a back rubber. Since it is bonded to the exposed surface of the tooth rubber, back rubber and tensile body with a rubber paste containing an organic compound having an isocyanate group in a rubber liquid dissolved in an organic solvent, the heat resistance and the tooth loss resistance are dramatically improved. It was possible to increase the belt life and lengthen the belt life.
Further, since the toothed belt according to the present invention is particularly excellent in tooth-missing performance, it can be used as a driving toothed belt to which the same load is applied even if the width thereof is narrower than that of the conventional belt. Furthermore, the toothed belt of the present invention has a high temperature,
Since it is excellent in heat resistance and tooth-breaking resistance under high load, it is particularly useful as a camshaft driving toothed belt of an automobile engine that requires high performance and high load.

[Brief description of drawings]

FIG. 1 is a perspective view of a toothed belt of the present invention.

[Explanation of symbols]

 1 tooth 2 tooth rubber 3 tooth cloth 4 back rubber 5 tensile body (core wire)

Claims (3)

[Claims] 1. A toothed belt comprising a tooth rubber, a back rubber, a tension member and a tooth cloth, wherein the tooth rubber and the back rubber are:
An organic perf containing one or more selected from the group consisting of organic acid higher esters and metal salts of acrylic acid or methacrylic acid as a co-crosslinking agent, and N, N′-m-phenylenedimaleimide. A toothed belt comprising a molded and cured product of an oxide crosslinked hydrogenated nitrile rubber composition. 2. The above hydrogenated nitrile rubber composition, wherein 100 g of the hydrogenated nitrile rubber polymer is used,
The organic peroxide is 0.30 in the amount of its —O—O— group.
1.51 g, 0.5 to 2.0 g of one or more selected from the group consisting of organic acid higher esters and metal salts of acrylic acid or methacrylic acid, and N, N'-m-phenylenedimaleimide The toothed belt according to claim 1, wherein the toothed belt contains 0.5 to 2.0 g. 3. A toothed belt comprising a tooth rubber, a back rubber, a tension member and a tooth cloth, wherein the tooth rubber and the back rubber are:
Organic peroxide crosslink containing N, N'-m-phenylene dimaleimide and one or more selected from the group consisting of organic acid higher ester and metal salt of acrylic acid or methacrylic acid as a co-crosslinking agent System hydrogenated nitrile rubber composition and one or more selected from the group consisting of organic acid higher ester and a metal salt of acrylic acid or methacrylic acid as a co-crosslinking agent, and N, N'- An organic peroxide-crosslinking hydrogenated nitrile rubber composition containing m-phenylene dimaleimide is dissolved in an organic solvent, and a rubber liquid is prepared by adding an organic compound having an isocyanate group to the rubber paste. A method for manufacturing a toothed belt, which comprises adhering to exposed surfaces of rubber and back rubber.